The earliest power converters operated until they exceeded the physical tolerances of their components, causing them to run the risk of catastrophic failure. In response to this patent deficiency, designers added current protection circuitry to prevent the power converters from exceeding a predetermined full rated output current. Even with current protection in place, excessive operating temperatures (typically caused by ambient environmental factors) still damaged the power converters.
In response to this further deficiency, designers provided thermal protection circuitry that sensed the temperature of the hottest component of the system and completely shut down the power converter when the sensed operating temperature exceeded a specified value. Until the specified value was exceeded, the power converters operated at their maximum output current level. Unfortunately, any load, regardless of size, suffered sudden power loss. What is needed in the art is a way to prevent unnecessary shutdown of power converters under excess temperature conditions.